The present invention relates generally to a heat tube device which is readily positionable about the cooling coil or coils of a conventional air conditioning system.
Conventional heat pipes are used for transporting heat from a heat source to a heat sink, with the heat sink being of a lower temperature than the heat source. Typically, one end of the heat pipe is exposed to the heat source while the other end of the heat pipe is exposed to the heat sink. The end of the heat pipe exposed to the heat source is normally known as the evaporator section of the heat pipe, while the end of the heat pipe exposed to the heat sink is normally known as the condenser section of the heat pipe. Heat is absorbed by a working fluid in the evaporator section which is in a liquid phase. Upon the absorption of heat by the evaporator section, the working fluid changes from its liquid phase to a vapor phase. The heat load picked up by the evaporator section is thereupon thermodynamically driven to the condenser section of the heat tube because of the temperature differential which exists between the heat source and the heat sink.
Upon the working fluid in its vapor phase reaching the condenser section of the heat tube, the heat load is rejected from the working fluid to the heat sink. This energy loss from the working fluid causes the working fluid to condense to a liquid phase in the condenser section of the heat pipe. Because the heat pipe may be a sealed system, the working fluid in its liquid phase may then return to the evaporator section of the heat pipe, typically by means of a capillary pumping structure located inside the heat pipe. Generally, the capillary pumping structure is an elongated wick carried in the heat pipe for substantially the entire length thereof.
Various types of capillary pumping structures are disclosed in U.S. Pat. No. 4,470,450, granted on Sept. 11, 1984 to Bizzell et al., entitled, "Pump-Assisted Heat Pipe", which include grooved inner wall surfaces being provided in the heat pipe.
A heat pipe finds particular use in a conventional air conditioning system. There, the evaporator section of the heat pipe is exposed to the warmer return air entering the air conditioning system prior to the return air passing over the air conditioner's cooling coils. Thus, the warmer return air acts as the heat source discussed above for causing the working fluid in a liquid phase in the evaporator section of the heat pipe to vaporize as the working fluid absorbs heat from the return air.
The condenser section of the heat pipe is positioned in the cold supply air flow of the air conditioning system on the other side of the cooling coils. Thus, the cold air coming from the cooling coils, to which the condenser section of the heat pipe is exposed, acts as the heat sink discussed above to which the heat load absorbed by the working fluid is transferred from the working fluid in its vapor phase. The transfer of the heat load from the working fluid in its vapor phase causes the working fluid to condense to liquid in the condenser section of the heat tube. The liquid may then be transferred by gravity or by some pumping means back to the evaporator section of the heat tube.
By using the heat tube with a conventional air conditioning system, the amount of moisture which can be removed from the return air can be increased without increasing the amount of cooling required from cooling coils. This is particularly advantageous in humid environments where the return air must first be cooled to a very low temperature for removing the required amount of moisture therefrom, and then reheated with electric heaters, steam heaters, etc., to make the supply air a temperature which is comfortable or which is required by the particular environment. This method of dehumidifying the air requires the use of a relatively large amount of energy, in that additional energy is required for the cooling coil to cool the air down for removing the moisture therefrom, and then further additional energy is required for heating the supply air back up to the desired temperature.
The heat tube allows for air to be pre-cooled by passing over the evaporator section of the heat tube so that the cooling coil does not have to cool the air quite as much, thereby allowing a reduced energy requirement. Moreover, as the cold air exits from the cooling coil, it is warmed by the condenser section of the heat tube, thereby eliminating the need for additional externally powered heat to be provided the exit air flow in certain applications. Because the heat tube is a sealed system which may operate without any moving parts, the heat pipe may require no additional energy input to the air conditioning system.
Various systems have been patented which utilize heat pipes. U.S. Pat. No. 4,607,498, granted to Dinh, entitled, "High Efficiency Air-Conditioner/Dehumidifier", discloses a heat pipe-type heat exchanger positionable about a coil of an air conditioning system.
U.S. Pat. Nos. 2,093,725 and 2,214,057, both granted to Hull, and entitled, "Refrigerating Apparatus", disclose secondary refrigerant systems positionable about an evaporator coil of a refrigeration system. The secondary refrigerator systems of the Hull patents disclose several means by which the performance of the secondary refrigerant system can be modified.
Other patented devices for air handling systems include the following U.S. Pat. Nos.: 2,438,120, granted to Freygang; 3,520,147, granted to Glackman; 3,640,090, granted to Ares; 3,916,644, granted to Nasser; 4,033,406 and 4,147,206, both granted to Basiulis; 4,044,797, granted to Fujie et al.; 4,061,186, granted to Ljung; 4,071,080, granted to Bridgers; and 4,438,636, granted to Morgan.
While several of the above-patented devices disclose the use of heat pipes, none is particularly adapted, as is the present invention, for being readily positioned about a cooling coil of a conventional air conditioning system. Further, none disclose such a heat pipe device which is readily adjustable in a manner as disclosed by the present invention for varying the heat transfer therefrom.